[SOLVED] Can I use Nexus+ 2 Fan Hub with only 3-pin fans?

[mk53v3n]

Hi guys,

I recently bought a new PC case (Fractal Design Define 7) which comes with a fan hub (Nexus+ 2) to which I can connect multiple 4-pin (PWM) as well as 3-pin fans.

I have a Noctua CPU cooler with 2 x 4-pin fans, but my case has only 3 x 3-pin fans installed.

I am wondering now if it makes more sense to either

(i) Connect ALL fans (CPU + case fans) to the fan hub and then connect the hub to the CPU_FAN port on the motherboard, or

(ii) Connect the CPU fans directly to the CPU_FAN ports on the motherboard, and connect the case fans to the hub and then the hub to a CHA_FAN port on the motherboard.

I am currently using option (i) as this is how the case manufacturer recommends it and it seems to work fine.

However, I read in other threads that it is usually more recommended to split CPU and case fans to control them separately.
Is this true, so is option (ii) really preferred?

If so, can I even do this with my setup? Since I only have 3-pin case fans, I am not sure if the fan hub would even work without one of the 4-pin CPU fans connected to it.
Unfortunately, this does not become clear from the user manual (although the user manual says that the first connected 4-pin fan is the one that reports RPM to the mainboard, so this is probably a hint that it would NOT work without at least one connected PWM fan...).

If anybody knows the Fractal Define 7 case and/or this fan hub and could give some advice here it would really be appreciated.

 

[DRagor]

Option 2 is preferred for no other reason that you do not want to mix 3 and 4 pin fans on one hub.
3 pin fans do not care about PWM signal at all so it does not matter whether you connect any 4 pin fan to hub - they will just run full speed no matter if PWM signal is delivered or not. And it is unlikely that hub would not work just because there are no 4 pin fans connected to it - those devices are not sophisticated enough. Also, you can try setting CHA_FAN control to DC in BIOS (if your mobo permits) and maybe that would let you control speed of 3 pin fans connected to hub (maybe because most hubs do not allow voltage control).

 

[mk53v3n]

Thanks alot for the quick reply.

I just changed it according to your advice and it works perfectly. 👍

 

[mk53v3n]

Unfortunately I have to take back what I wrote a couple of days ago ;(

After only connecting 3-pin-fans and the SATA power cable to the fan hub, I noticed that my PSU (Seasonic TX-1000) started to produce a pulsing noise.

I couldn't clearly identify it at first, but after experimenting a little bit I found out that this pulsing noise disappears as soon as I connect a 4-pin-fan (in addition to the 3-pin-fans) to the hub and in turn the hub via the attached PWM-cable to the motherboard.

So something seems to be wrong here...

The only question is - could this be an issue with the fan hub or with the PSU (or some kind of incompatibility between the two)?

Any advice on this would greatly be appreciated.

 

[DRagor]

could this be an issue with the fan hub or with the PSU (or some kind of incompatibility between the two)?

Incompatibility - no. The only thing that connects PSU and hub - the SATA cable - is standard. There can be no issues from this side.
But it could be some failure of either hub or PSU. Or it could be 'feature' of the hub.

I noticed that my PSU (Seasonic TX-1000) started to produce a pulsing noise.

Are you actually sure its PSU that makes noise? Not one of the fans? It would be pretty unusual for PSU to make noise because something is connected to SATA cable ...

pulsing noise disappears as soon as I connect a 4-pin-fan (in addition to the 3-pin-fans) to the hub and in turn the hub via the attached PWM-cable to the motherboard

The hub should be connected to motherboard no matter what. Check if that alone will not fix the problem. The other possible option is to not use SATA cable - the fans use only 0.2 A so three of them on single header will work without supplemental power. I don't know however if that will work as the SATA cable might be necessary for basic hub operation.
Also checked the case manual and it seems the hub will turn PWM control signal from motherboard to DC signal, so it will let you control 3-pin fans with PWM cable. On the other hand it is not necessary as those case fans are built in such way to operate full speed all time (only 19dB noise).

 

[mk53v3n]

The hub should be connected to motherboard no matter what.

This was the problem. I spoke with the manufacturer and they confirmed that the HUB will not work properly if it is not connected to the motherboard.

In the end, I decided to replace the pre-installed fans with 3x Noctua PWM fans and additionally buy a higher-quality hub, so I can easily connect them to the motherboard and control them more comfortably.